text: In terms of molecular structure, one distinguishes first between low-molecular-weight (LMW) and high-molecular-weight (HMW) products. The generally accepted threshold between LMW and HMW is a molecular weight of about 700. LMW fine chemicals, also designated as small molecules, are produced by traditional chemical synthesis, by microorganisms (fermentation or biotransformation), or by extraction from plants and animals. In the production of modern life science products, total synthesis from petrochemicals prevails. The HMW products, respectively large molecules, are obtained mainly through biotechnology processes. Within LMWs, the N-heterocyclic compounds are the most important category; within HMWs they are the peptides and proteins.